Electric unmanned aerial vehicle launcher

ABSTRACT

Embodiments of the present invention provide improvements to UAV launching systems. The disclosed launching system eliminates the use of hydraulic fluid and compressed nitrogen or air by providing an electric motor-driven tape that causes movement of a shuttle along a launcher rail.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 61/870,281, filed Aug. 27, 2013, titled “Electric UAV Launcher,” theentire contents of which are hereby incorporated by reference.

FIELD OF THE DISCLOSURE

Embodiments of the present disclosure relate generally to anelectrically powered launcher system designed to launch an unmannedaerial vehicle (UAV). The embodiments of this electrically poweredlaunch system provided are generally more lightweight than currenthydraulic-pneumatic launching systems. They also do not use hydraulicfluids and fuel for an engine for the launching process. This rendersthe system environmentally sound because fumes and spills may beeliminated. Through the use of feedback-based controls tied into a drivemotor, the launch acceleration profile can be programmed and potentialg-load spikes mitigated.

BACKGROUND

Launching systems for unmanned aerial vehicles (UAV) are designed tocreate enough force and speed that the UAV can be ejected into the air.The general concept behind a UAV launching system is to take a vehiclefrom rest to the desired flight velocity in a minimum distance, withoutimparting destructive forces to the vehicle. UAV launcher systems forvehicles weighing thirty pounds or more typically use a pneumatic orpneumatic/hydraulic system as the prime propulsion system.

The traditional approach to take-off for many UAVs (including taxi,accelerate, lift-off, and climb) often requires a distance of 200 feetor more. This traditional take-off minimizes the acceleration (g-load)on the vehicle because it is accelerated over a longer distance.However, there is a desire to design systems that can obtain the desiredlaunch velocity in less than 50 feet in some instances. For example, onshipboard applications and other instances, space may be limited. Inaddition, the landing gear associated with runway take-off and landingoperations adds weight and thus requires more power and fuel to sustainflight operations.

However, the use of a launcher that allows shorter distance to achieveflight (because the acceleration is faster) generally means higherg-loads. There are often expensive electronics on-board the UAV thatcannot withstand such high g-loads. Other limitations to launchparameters include a minimum launch velocity or a maximum space tolaunch. The design and optimization of the launcher then becomes abalance of launch stroke length, vehicle acceleration, vehicle weight tobe launched, and launch angle.

The power source for the UAV launchers designed to date has typicallybeen a self-contained power source in the form of a closed loophydraulic/pneumatic system, which stores energy when dry nitrogen iscompressed in an accumulator by pumping in hydraulic fluid. Thehydraulic pump is usually driven by either an electric motor, a gasolineengine, or by a multi-fuel engine.

Historically, closed loop hydraulic-pneumatic systems have proven to bethe most reliable and repeatable under the widest range of environmentalconditions. To prevent condensation at extreme temperatures, drynitrogen (GN₂) is used, instead of air, to fill the “pneumatic” side ofa piston accumulator. The nitrogen is pre-charged to a pre-determinedpressure. A hydraulic pump then pressurizes the hydraulic side of theaccumulator piston, which compresses the nitrogen and raises the launchpressure. Once the optimal launch pressure is reached, the system holdsthe pressure via check valves until launch is initiated. Upon launchinitiation, the valve opens, the nitrogen expands, pushing the fluid outof the accumulator and into the cylinder. This accelerates the cylinderpiston, the reeving cable, shuttle and vehicle.

However, there are some limitations and problems associated withpneumatic launchers. For example, there is typically an accumulatorassociated with the system that must be pre-charged to a specificpressure to achieve the desired launch velocity for a given UAV weight.If a different speed is required or if the weight of the UAV varies (dueto fuel load or ordinance), the pre-charge pressure must be adjustedaccordingly. This generally requires that gas (typically air or drynitrogen) either be bled from or added to the system via a separate gasbottle. The need to vary the pressure adds to system complexity andpotentially increases the overall system weight (e.g., if a gas bottlepositioned on-board the launcher is used).

With a pneumatic launcher, it can be also difficult to control theg-load imparted to the UAV when the pressure is released into themechanical drive components at the initiation of the launch cycle. Thesespikes in the g-load at the beginning of the launch cycle can havepotentially disastrous impacts on the UAV and the on-board electronicsand other systems. These initial g-load spikes can be mitigated throughcontrol valves that release the hydraulic fluid from the accumulatorinto the drive cylinder in a controlled fashion. However, these valvesare often expensive and add weight to the overall system.

Additionally, many UAV launchers are used in an expeditionary mode,where they need to be mobile and capable of being transported to alocation for deployment. In some cases, they may be mounted to the backof a truck. In other cases, they may be trailer mounted and either towedinto position or slung from the underside of a helicopter and air liftedinto position. In most cases, the overall size and weight of thelauncher system must be minimized to ensure that it can fit withincertain aircraft or transport containers. The main drive components of ahydraulic/pneumatic launcher (accumulator, pump, launch cylinder, gasbottle, reservoir, etc.) add substantial weight to the system, andweight is a primary limitation to mobility of the system.

With any hydraulic/pneumatic system, leaks are always a concern. Loss ofgas pressure or a hydraulic leak could potentially shut down operations.Once fielded, it is unlikely that there will be access to gas cylindersto address leaks in the system.

Launch timing can also be an issue with a hydraulic/pneumatic system.Depending on the differential between the pre-pressure and final launchpressure, the size of the pump and amount of hydraulic fluid to bemoved, it can take up to several minutes to bring the system up tolaunch pressure. The UAV is typically mounted on the launcher, and itsengine is running during this pressurization time, making it susceptibleto overheating.

Reset can be another challenge presented by a hydraulic/pneumaticsystem. Resetting a hydraulic/pneumatic launcher after completion of alaunch requires that the shuttle be pulled back into the launchposition. This may take several minutes because, as the shuttle ispulled back, the hydraulic fluid needs to be pushed out of the cylinderand back into the reservoir. The time required to reposition the shuttlenegatively impacts the overall cycle time.

One launcher design that does not use a hydraulic system is described inU.S. Pat. No. 4,678,143. The launcher described by this patent uses aflywheel that provides the energy required for the launch sequence. Theflywheel is spun up by a small electric motor that is powered by agenerator, and an electric clutch engages the flywheel when the launchcycle is initiated. The flywheel drives a cable drum that wraps cablearound the drum during the launch sequence. One of the disadvantageswith this launcher is that the flywheel may take several minutes to comeup to launch speed. Another disadvantage is the requirement of agenerator as a power source, which can add a great deal of weight to thesystem.

BRIEF SUMMARY

Improvements to UAV launching systems are thus desirable. In particular,improvements that eliminate the use of hydraulic fluid and compressednitrogen or air are desirable. Improvements that eliminate the use of aflywheel to provide energy fix a launch sequence are desirable. Systemsthat are lighter, more reliable, allow more control of g-load, that donot threaten leaks, that do not take several minutes to launch, and thatdo not take several minutes to reset are desirable.

Embodiments described herein thus provide a launching system for anunmanned aerial vehicle that uses a launcher rail, a shuttle configuredto travel along the launcher rail, and a drive mechanism for moving theshuttle along the launcher rail. The drive mechanism can include alength of tape secured to the shuttle, an electric drive motor thatdrives movement of the tape, and a drive reel to which one end of thetape is secured and around which the tape is wound during launch. Thetape may be nylon, a nylon blend, or some other material. The electricmotor may be a DC motor or some other motor that comports with theweight and size requirements for the particular system. The electricmotor may be battery powered. In a specific design, the electric motoris powered by a Lithium Ion battery.

This disclosure provides a UAV launching system that provides launchusing completely electric launch components, including the braking andcontrol system. There are no hydraulic systems on board that couldpresent environmental issues in the event of a leak. The launch systemdescribed may be mounted to a base or pallet that can in turn be mountedto a trailer, dolly type wheel base, a flat bed truck, train flat car,ship deck, or any other appropriate launching location or surface. Themodularity of the components used also allows scalability for higherenergy UAV launches.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side plan schematic view of one embodiment of a launchingsystem, using an electric motor-driven power reel and a payout reel tomove a shuttle along a tape.

FIG. 2 shows a perspective view of a launcher rail at an angle, withouta shuttle in place.

FIGS. 3A-C show a launch series with a UAV being released from ashuttle.

FIG. 4 shows a side plan schematic view of the launching system of FIG.1, with the shuttle being detached from the tape.

FIG. 5 shows a side plan schematic view of a launching system that usesend sheaves for controlling winding of the tape.

FIG. 6 shows a side plan schematic view of a launching system with ashuttle that remains secured to the tape.

FIG. 7 shows a side plan schematic view of a launching system that usesa power reel, without a payout reel.

FIG. 8 shows a side perspective view of a launching system that uses acable wrapped around a drum, driven by the motor, and pulleys on theshuttle.

FIG. 9 shows a free body diagram of the embodiment of FIG. 8.

FIG. 10 shows a side view of a launching system with panels that can beused to help raise the tape for folding of the rail.

FIG. 11 shows a side plan schematic view of a launching system that usesa conveyor belt.

FIG. 12 shows a side view of an alternate conveyor belt system.

FIG. 13 shows a side view of a launching system using a steel cablewound around a drum and driven by an electric motor.

FIG. 14A shows one embodiment of a braking system that may be used for alaunching system.

FIG. 14B shows a schematic view of the braking system of FIG. 14A.

FIG. 15 shows a side plan schematic view of a launching system in use.

FIG. 16 shows a schematic illustration of a mechanism that may be usedto secure a shuttle to a cable.

DETAILED DESCRIPTION

UAV launchers may be offered with fixed or mobile installation, variousrail options (telescoping rails or elongated fixed rails), manual orautomated operation, and designed for a variety of UAV configurationsand designs based on desired performance and cycle times. The systemsdescribed herein may be used on any of the various types of launchingsystems. In one embodiment, the launching system described may bemounted on a motor vehicle that can transport the launching system tothe desired location for launch. The launch may occur while the systemis on the vehicle, or the system may be removed from the vehicle forlaunch. In another embodiment, the launching system described may beinstalled at a fixed location.

As shown in FIG. 1, in one embodiment, there is provided a launchingsystem 10 that uses a motor-driven belt or tape mechanism 12 that isattached to a shuttle assembly 14. The shuttle 14 is the carrier thattransfers the energy required for launch to the UAV. As shown in FIG. 2,the shuttle 14 may travel along a length of a launcher rail 16. Thelauncher rail 16 is typically inclined. This incline may be achieved bystruts 18 that rest on a surface or are secured to a surface. Struts maybe secured to a base or pallet that may be mounted to a trailer, wheelbase, flat bed truck, train flat car, ship deck, or any other surface orvehicle designed for launching. Alternatively, the struts may rest on aground surface. The launcher rail 16 may be a fixed track of fixedlength or it may have an extendable boom that elongates the rail. Forexample, the extendable boom may be hinged, such that it could be foldedand the length would not be obtrusive to typical transport methods. Inanother embodiment, the extendable boom may be driven out from aretracted position, or may be extended in any other appropriate mannerto elongate the launcher rail 16 into an extended track if needed. Thelauncher rail 16 length is typically contingent on the distance requiredto achieve the desired final launch velocity, without exceeding apre-defined g-load threshold of the UAV, as well as the distancerequired to stop or arrest the shuttle. FIG. 2 also shows that one ormore batteries 64 may be positioned on a base 66, along with one or moremotor control components 68.

The launcher rail 16 may be used to guide the shuttle 14 along the drivelength 20 of the rail 16, in the direction of launch, illustrated by thearrow in FIG. 1. (For ease of review, FIG. 1 does not show a launcherrail or an incline, although both would generally be incorporated into afinal launch system.) As the shuttle 14 travels along the rail 16, themotion of the shuttle 14 transfers the launch velocity to the UAV. (FIG.1 does not show a UAV secured to the shuttle 14. FIGS. 3A-C show apotential launch sequence.)

Rather than securing a cable to the front of the shuttle, which is howmost current launching systems work, the shuttle 14 is secured to a tape12 that runs the length of the launcher rail 16. More specifically, abelt or tape 12 is used to cause movement of the shuttle 14 along thelauncher rail 16. The shuttle 14 is generally secured to the tape 12 ata shuttle to tape interface 22. This interface 22 may be any appropriateconnection. In one embodiment, the shuttle to tape interface 22 may beprovided as a pin 24 attached to the tape that cooperates with acorresponding structure on the shuttle 14. This embodiment is shown inFIGS. 3A-C and 15. For example, the undercarriage of the shuttle mayhave a hook 26 or some other detachable connection feature attachedthereto that cooperates with the pin 24. In another embodiment, theinterface 22 may be formed from any type of upward protrusion 28 on thetape 12 that is shaped to cooperate with a lower protrusion or hook onthe shuttle. In another embodiment, the interface 22 may be annon-detachable connection between the shuttle and the tape. In anotherembodiment, the interface may be formed as a clamp, where the shuttlesecures two ends of the tape to one another at a location on theshuttle. Other connections are possible and within the scope of thisdisclosure.

In use, a UAV is secured to an upper surface of the shuttle 14 as shownin FIGS. 3A-C. The attachment of the UAV to the shuttle 14 may be viaany appropriate connection currently in use or as may be developed,including any of the above described options. An abrupt stoppage of theshuttle 14 causes the UAV to launch off of the shuttle 14.

The tape 12 may run along the drive length 20 of the launcher rail 16.In one embodiment, its ends are generally secured to one or more of apayout reel 36 and/or a power reel 30, as shown in FIGS. 1, 4-6, and 15.In another embodiment, one end of the tape 12 may be detachably securedto the shuttle and one end is secured to a power reel, as shown in FIG.7. In another embodiment, a cable is used, and the cable is wrappedaround a drum, driven by the motor, as shown in FIGS. 8-9. In anotherembodiment, the tape 12 is a continuous tape that runs as a conveyorbelt along the launcher rail, as shown in FIGS. 11-12. In anotherembodiment, a steel cable or rope may be wound around a pair of drums90, as shown in FIG. 13. In another embodiment, an alternate brakingsystem may be provided, as shown in FIGS. 14A-B. Each of theseembodiments is described in further detail below.

The tape 12 may be formed of a material that has more elasticity orstretch than cables used in typical launching systems. For example, thetape 12 may be formed from nylon, a nylon blend, or another syntheticmaterial. In some embodiments, the tape may be formed of a material thathas an amount of inherent stretch. The stretch inherent in the materialused can help mitigate the g-force during the initial application oflaunch load. However, the stretch of the material is not required. Inother embodiments, tapes or belts containing metallic reinforcing fibersmay be used. The electronic control system in conjunction with theelectric motor can be used to tightly control the acceleration profileof the launch cycle.

In the embodiment shown in FIG. 1, a tape 12 is attached at one end to apower reel 30, which is mounted to a drive shaft 32 of an electric motor34. Details of the electric motor are described more below, but in oneembodiment, the electric motor 26 may be a DC motor. The electric motor34 is what drives movement of the tape 12. In use, the electric motor 34remains stationary with respect to the launcher rail 16 and theremainder of the shuttle guiding components.

The opposite end of the tape 12 may be attached to a payout reel 36. Asshown in FIG. 1, the payout reel 36 may generally be positioned near abattery position end 38, and the power reel 30 is generally positionednear a launching point 40 of the launching system 10. Once the electricmotor 34 is energized, the motor rotates the power reel 30, which windsin the tape 12 from the payout reel 36. This winding of the tape 12accelerates the shuttle 14, which is attached to the tape 12 (andconsequently accelerates the UAV, which is attached to the shuttle 14).The payout reel 36 contains at least a sufficient length of tape 12 thatallows full travel of the shuttle 34 up the rail.

As shown in FIG. 1, the shuttle 14 may be connected to the tape 12 via ahook 26 (or some other detachable connection on the undercarriage of theshuttle 14) that attaches to an interface 22 on the tape. In theembodiment shown, the interface 22 is provided as a pin, protrusion 28,or other raised structure that can interface with the shuffle hook.Actuation of the electric motor 34 causes movement of the shuttle 14along the power zone 100. The shuttle 14 accelerates to launch velocityover the entire length of the tape 12 in this zone 100. It should beunderstood that the rail is not shown in FIG. 1 and that there will besufficient rail length beyond the shuttle to tape separation point 40 inorder to bring the shuttle to an abrupt stop.

FIGS. 3A-C show a sequential series illustrating a shuttle 14 with a UAV70 positioned thereon, and its travel along the tape 12. In FIG. 3A, theshuttle 14 is shown traveling along the rail 16. In FIG. 3B, the shuttle14 is shown engaging an arrestment strap 72. The arrestment strap 72functions to stop forward momentum of the shuttle 14. In this figure,the shuttle 14 has just engaged the arrestment strap 72 and the UAV 70is ready to depart the shuttle 14. In FIG. 3C, the arrestment strap 72has stretched to absorb shuttle energy, and the UAV 70 has beenreleased.

In some examples, when the shuttle 14 reaches a shuttle to tapeseparation point 40 or another launching point, the shuttle 14 may bereleased from the tape 12. This release generally occurs once theinterface 22 on the tape is wrapped around the end of the power reel 30,as shown in FIG. 4.

In the embodiment of FIG. 4, the shuttle 14 is allowed to release fromthe tape 12. A shuttle 14 that separates from the tape 12 can eliminatethe need for precise timing because the tape does not have to stop at aparticular point. Stopping the released shuttle 14 may be accomplishedvia an arrestment strap, a braking mechanism at the end of the rail, abraking system on-board the shuttle itself, or any other appropriatesystem. As shown in FIG. 4 (and as also illustrated by the launch seriesof FIGS. 3A-C), an abrupt stop of the shuttle 14 in the shuttle brakingzone 102 may release the UAV from the shuttle 14. (This may be inaddition to the shuttle 14 also releasing from the tape 12.)

In the embodiment shown in FIG. 5, end sheaves or pulleys that provide apath for the tape may be mounted on or below or otherwise with respectto the launcher rail 16. A first sheave 46 may be mounted at the batteryposition end 38. A second sheave 48 may be mounted at or near thelaunching end 40. In another embodiment, the second sheave 48 may bemounted at some length before the launching end 40 of the rail 16 inorder to allow distance for the shuttle 14 to be arrested at the end ofthe power stroke. In use, the first sheave 46 routes the tape 12 fromthe payout reel 36 over the upper horizontal surface 50 of the launcherrail 16 to the second sheave 48. The tape 12 may then be routed over thesecond sheave 48 down to the power reel 30. The power reel 30 and thepayout reel 36 may be mounted to the underside of the launcher rail 16,as shown in FIG. 5. In an alternate embodiment, the power reel 30 andthe payout reel 36 may be mounted to a base on which the launcher rail16 may be mounted.

Use of first and second sheaves 46, 48 can lend advantages to the system10. For example, the increase in the diameter of the power reel 30 dueto the tape 12 being wrapped onto it during the power stroke could leadto interference with the shuffle 14. Routing the tape 12 over an endsheave 48 and positioning the power reel 30 underneath the launcher railcan lessen the chance that the increase in the tape 12 stack couldimpact movement of the shuttle 14. Likewise, the same condition existsat the payout reel 36 end, but the diameter of the tape 12 on the payoutreel 36 decreases during the power stroke, due to the tape 12 beingpulled from the payout reel 36. This could also lead to the tape 12interfering with the launcher rail 16. Positioning the payout reel 36under the launcher rail 16 also provides space at the battery positionend 38 of the rail, where the UAV is to be loaded onto the shuttlecarriage 14. Additionally, the added distance between the power reel endsheave 48 and the power reel 30 itself can allow the power stroke to beshut down prior to when the shuttle/tape interface 22 would be wrappedonto the power reel 30. Wrapping tape 12 over this interface 22 couldpotentially deteriorate the tape.

In another embodiment shown in FIG. 6, the shuttle 14 may benon-removeably secured to the tape 12. For example, the undercarriage ofthe shuttle 14 may feature a connection that completely captures theshuttle to tape interface 22, which may be a pin or other componentsecured to the tape 12. The tape 12 may be manufactured from acontinuous strip of material. In another example, the tape 12 may bemanufactured from a non-continuous strip of material. For example, ifthe tape 12 is not fabricated from a single continuous strip, twosections can be used and connected to the tape interface 22. Using twotape sections may be advantageous in that the section connected to thebraking reel could be fabricated from a different and potentially higherstrength material to help aid in braking the weight of the shuttle. Thisinterface 22 generally prevents the shuttle 14 from disengaging from thetape 12. As shown, the shuttle 14 stops in a braking zone 102 before theend of the rail. The UAV is released from the shuttle 14 in this brakingzone 102. The tape 12 may be used to arrest the shuttle 14 via a brakingsystem 54 contained on the payout reel 36. In one embodiment,electrically actuated brakes may be used to prohibit the use ofhydraulic fluids or pneumatic brakes. An optional arrestor strap orsecondary braking system (as described previously) may also be used tosupplement the shuttle 14 arrestment.

In another embodiment, the payout reel 36 could be eliminated, as shownin FIG. 7. In this embodiment, the power reel 30 is used to acceleratethe shuttle 14 and the tape 12. The power reel 30 may be associated withthe electric motor 34 as described above. After the shuttle 14disengages, the tape, including the interface/pin 22, would wrapcompletely around the power reel 30. The shuttle 14 arrestment may bethrough an arrestment strap, a rail based brake, or an on-board shuttlebrake.

Another embodiment may use a cable 78 that is wrapped around a drum 82,driven by the motor 84. One example of which is shown in FIGS. 8 and 9.In this embodiment, the shuttle 14 has two pulleys 74, 76 located on itslower surface. One pulley 74 may serve as the launch guide for the cable78. The other pulley 76 may serve as an arresting guide. A braking drum80 may act as an anchor point for launch. A winding drum 82 reels in thecable 78 to propel the shuttle 14 down the rail 16. Two fixed pulleyassemblies 120, 122 may be located along the rail 16, mounted toopposite sides of the rail 16. Each fixed pulley assembly 120, 122 mayactually comprise two or more pulleys, as shown. In the embodimentshown, the fixed pulley assemblies 120, 122 may be located on the rail16, at the location where the cables come in from the braking drum 80and the winding drum 82. The cable 78 pulls against pulley 76 (on theshuttle) until the shuttle 14 crosses the rail section where the cablescome in from the braking drum 80 and the winding drum 82. At that point,the cable 78 flips to pulley 74 on the shuttle for the braking action.This may be referred to as “flexing.” Accordingly, when the shuttle 14crosses the point on the rail 16 where the two fixed pulley assemblies120, 122 are located, the cable 78 transitions from the shuttle's launchpulley 76 to its arresting pulley 74. The winding drum 82 may be stoppedwith a brake. The braking drum 80 may allow some pay-out of the cable 78as it brings the shuttle 14 to a stop. FIG. 8 also shows an arrestingstrap 72 in place along the rail 16. The strap 72 extends along eitherside of the rail with a center strap portion 73 crossing over the rail.

In a specific example, a synthetic rope may be used as the cable 78.This may help alleviate possible issues with flexing a steel cablearound a small pulley and then reversing the direction of flex suddenly.

Many of the particular designs described herein have generally used aflat tape 12 that runs almost the entire length 20 of the launcher rail16. In some embodiments, the rail 16 may need to be folded for transportand the tape may lie perpendicular to the direction of the fold. In thiscase, it is possible to provide a set of “paddles” 86 that may be addedto the rail sections 16 adjacent to hinges. One example of this is shownin FIG. 10. The paddles 86 may be provided in order to raise one edge ofthe tape 12 above the rail flanges 17, such that the paddles 86facilitate folding of the rail 16 through the thin section of the tape12. The paddles 86 may tilt the tape 12 at an angle to allow it to foldthrough its thin section. In another variation, the tape 12 could bemounted at about 90 degrees to this design such that the flat sectionwould be in the plane that the hinge rotates.

In a further embodiment shown in FIG. 11, a conveyor configuration maybe used. In this embodiment, one or more electric motors 34 drive apulley that moves a continuous loop belt or chain 56. The continuousloop belt or chain 56 can engage the shuttle 14 in any of theabove-described ways. Once the shuttle 14 reaches the end of the powerstroke, it disengages from the belt 56. The shuttle 14 may be arrestedvia an arrestment strap or any other braking system. In anotherembodiment, the shuttle may be securely attached to interface 22 and thebraking forces applied through the conveyor belt.

FIG. 12 shows a schematic of an alternate conveyor concept. This conceptutilizes a shuttle 14 that is restrained to a drive belt 56 as the tape12 that provides a continuous loop. The shuttle 14 may function as aclamp that holds the end of the belt together. A drive motor 34 mayconnect to an input shaft 104. A drive pulley 106 may be connected via asprocket and chain to the drive motor output shaft or it may be directlyconnected to the motor output shaft. Shuttle braking may be accomplishedby variable electric braking, by an arresting strap variation, or by anyother appropriate method. In this embodiment, the shuttle is connecteddirectly to the belt to form the continuous loop. This implies that theshuttle must be stopped prior to reaching the end pulley 108 during alaunch or the shuttle would attempt to wrap around 108. Anotherembodiment may have the shuttle 14 disconnect from the drive belt priorto reaching pulley 108.

An alternate launching embodiment is shown in FIG. 13. This concept mayuse a continuous steel rope 88 wound around a pair of drums 90 whichhave spring tension forcing them apart and applying force to increasefriction between the steel rope 88 and the drums 90. One of the drumsmay be coupled to the drive motor assembly 92 through a belt or chain.This allows the capstan drums 90 to be mounted to the rail for ease ofrail tilting for adjustment of launch angle. The shuttle 14 may beattached to the rope 88 by a mechanism 126 similar to that used for aski lift. At the end of the stroke, variation in the shuttle wheel guidespace can allow a clamping mechanism to open, and the shuttle 14 canfreewheel into an arresting strap.

In one example, as shown in FIG. 16, the clamping mechanism 126 may beattached to the bottom of a shuttle and may be used to secure theshuttle to the cable. In the clamped position, wheels 128 may ridewithin rail slots in order to constrain the clamp mechanism. Upper railguides 134 may hold the cable gripping jaws 132 closed such that thegripping jaws 132 are clamped over cable 88. In the released position,the jaws 132 release. This can be accomplished when the wheels 128,which may be spring-loaded wheels, proceed beyond the upper rail guide134. In one embodiment, the upper rail guides are tapered along thelength of the rail to allow transition from the open to the clampedposition.

In another embodiment, an alternate braking mechanism may be provided.One example is shown in FIGS. 14A and B. This variation provides anarresting tape 97 that may be attached to the shuttle. For example, theback end of the shuttle 14 may be connected to an arresting tape 97 thattrails behind the shuttle. The arresting tape 97 can be wound onto thetape reel 96 with a clutch, brake, and rewind motor. The launch tape 12may be secured to the shuttle 14 using any of the options describedherein. The launch tape may be driven by the drive motor assembly 94 formoving the shuttle 14 along the rail 16 as described herein. The drivereel 92 is shown directly to the right of the braking reel 96, and asprocketed drive reel 124 is shown just under the drive reel 92. Asshown, a sprocket 124 and chain may be used between the motor 94 and thedrive reel 92. FIG. 14B shows a schematic of this braking option.

The launch tape 12 and the arresting tape 97 may be of differentmaterials to obtain different performance characteristics. Although thismay add drag to the system, it allows for automatic rewind and canprovide a “hands off” arrangement. This may provide a launching systemthat can be a self-deploying launcher.

For this braking embodiment, the timing of the launch to arrestmentsequence may be critical. The shuttle 14 can be traveling up to about140-145 feet per second when the transition from launch to arrestmenttakes place. The timing of the launch signal may be delivered from aProgrammable Logic Controller (PLC) to a drive controller in order toshift the motor from powered launch to coast, while engaging the brake.A fast responding and repeatable brake may be provided to ensuresuccess. This system may be provided with an electric brake to eliminatethe need for hydraulic braking systems. However, a hydraulic brake maybe used. The brake may be variable in order to adjust to differentweights and speeds.

FIG. 15 shows one embodiment of a launcher system 10 with the launcherrail 16 inclined at an upward angle, and with the shuttle 14 positionedon the tape 12 on the rail 16. This embodiment provides a batteryposition sensor 58, which is activated when the shuttle 14 is in abattery, or pre-launch, position. When the shuttle 14 is pulled back tothe battery position, it activates sensor 58. Activation of the sensor58 activates a brake on the payout reel 36 to keep the tape taught. (Insome embodiments, for safety purposes, the launch sequence cannot beinitiated unless the shuttle has been secured in the battery position.)When launch is activated, the electric motor 34 is energized and thebrake on the payout reel 36 is disengaged. Disengaging the brake allowsthe shuttle 14 to move along the rail 16. The motor 34 activates thepower reel 30 to wind the tape, causing movement of the tape 12 and theattached shuttle 14. A power reel shutdown sensor 60 may be positionedalong the rail 16, toward the launching end 40. When the shuttle 14reaches this sensor 60, a signal is sent to the motor 34 to stopmovement of the power reel 30 and/or to activate payout reel 36 brakes.The tension in the tape 12 created by the stopping and/or braking actionabruptly stops the shuttle and causes release of the UAV. If theembodiment in which the shuttle releases from the tape 12 is used, thenthe shuttle may be stopped by an arrestment strap or other stoppingfeatures, which abruptly stops the shuttle and causes release of theUAV.

In many of the above embodiments, the electric motor 34 is shut downimmediately prior to the arrestment of the shuttle 14 such that themotor does not continue to supply power and potentially damage theshuttle or drive mechanisms. The payout reel 36 may also be connected toa rewind motor that can retract the tape 12 into the battery (or launch)position such that another UAV could be quickly loaded and readied forlaunch. Applying the power stroke by reeling in tape 12 in this mannerto achieve the launch velocity is not used on any other commerciallyavailable launchers.

In some embodiments, it has been found that a DC motor providesdesirable driving features and speeds. The electric motor may be used inconjunction with a battery system to enhance portability. The batterymay be a Lithium Ion battery system. The electric motor may also be usedin conjunction with a Programmable Logic Controller (PLC). The PLC canallow the motor RPM (revolutions per minute) to be adjusted as requiredthroughout the launch sequence to provide a controlled acceleration andthus mitigate the high initial G-spikes typical of a hydraulic/pneumaticsystem. Use of a PLC also allows the ability to dial in the launchloads, making it easy to adjust for weight or speed variances andeliminating the need for time consuming changes to the launchpre-pressure by adding or purging gas from the system. For example, theG force may be minimized by programming the shape of the G force curvein the controller.

The functions of the PLC could possibly be integrated into drive controlfunctions and be combined into one unit. Alternatively, the PLC may be aseparate component that can be optionally added to the system.

One specific embodiment of a motor that may be used with the electriclauncher is a DC motor propulsion system and controller. This motor canbe powered by a Lithium Ion battery. Other types of electric motors maybe used. For example, an AC motor with a similar torque output may beused. However, it is believed that such an AC motor would besignificantly larger and heavier than the DC motor. The DC motor waschosen for the initial application based on the ability of the batteriesto supply a surge of current that is typically not available from ACpower sources. Alternately, AC power with suitable transformers anddischarge capability could be used to power the DC motor.

Additionally, more than one motor can be used to provide the loadrequired for launch. Through modularization, it is possible to usemultiple motors to scale up the system to accept UAV's with greaterweight or where increased power is required for higher launchvelocities.

Use of one or more electric motors means that the acceleration achievedcan be tightly controlled along the entire length of the power strokewithout the need for complicated control valves and manifolds requiredon hydraulic/pneumatic systems. In pneumatic and pneumatic/hydraulicsystems, the maximum acceleration typically occurs at the beginning ofthe launch because this is where the system pressure is at its maximum.As gas expands into the cylinder, the pressure drops and the forceapplied to the shuttle decreases. By contrast, a constant accelerationcan be provided over the entire launch stroke utilizing the electricmotor-driven tape described herein, because the motor RPM can increasedthroughout the stroke. The use of the DC motor in conjunction with thePLC to accurately control the launch profile is a unique to many of theabove-described problems with commercially available launch systems.

The use of the tape 12, which may be fabricated from nylon or some othersynthetic material, offers a degree of cushioning during the initialapplication of the launch load since there is an inherent amount ofstretch associated with this type of material. Most hydraulic/pneumaticsystems connect the drive cylinder to the shuttle via a steel cable thatdoes not have as much compliance or stretch during the application ofthe load and can exacerbate the g-load spikes seen. Use of a tape thathas some cushioning, flexibility, stretchability or other features thatallow a slight elongation and retraction of the material can bebeneficial in the launching systems disclosed. It should be noted,however, that the stretch in the synthetic tape or belt is not required.Tapes or belts containing steel reinforcing fibers that would lesson oreliminate stretch may also be used. The use of a shuttle to tapeinterface allows the ability to control the acceleration byprogrammatically increasing the launch speed. This can be a primecontributor to eliminating the g-load spikes that occur with othersystems.

The use of the Lithium Ion battery power source and electric motor asthe drive mechanism can greatly reduce the overall system weight whenjudged against a comparable system containing the requiredhydraulic/pneumatic components (accumulator, pump, launch cylinder, gasbottle, reservoir, weight of hydraulic fluid, and so forth). It alsoallows for greater flexibility in the layout of the system and theability to potentially modularize some of the subsystems. The componentsused may be smaller and do not require large tubes or pipes to route thepressured hydraulic fluid or gas. Power cables or flexible bus barscontaining connectors can be used to route DC current from the batteryto the motor. This will allow rapid replacement of a discharged batteryunit.

It should be understood, however, that the battery need not be Lithiumion. Any other battery system capable of providing the required load anddischarge rates may be used. Lithium Ion was chosen for an initialapplication due to its low weight and rapid discharge characteristics.It is expected, however, that other battery types and systems may beused in connection with this disclosure.

Since there are no pressure vessels utilized in this disclosure, theproblem of gas or hydraulic leaks has been eliminated and the overallsafety of the system has been enhanced. In many of thehydraulic/pneumatic systems, the cylinder and possibly the accumulatorare attached to the rail. The accumulator is often piped over to a largegas bottle that serves as a reserve vessel to store pressured GN₂. Dueto the piping between the various hydraulic and pneumatic components, itcan be difficult to allow the rail to move relative to the base if anadjustable launch angle is desired. By contrast, the ability to mountthe drive motor 34 and payout reel assembly 36 to a base plate or palletunder the launcher rail 16 allows the rail to be unencumbered by excessweight and complexity. Utilizing a tape path that routes around the twoend sheaves 46, 48 on the rail can allow the rail to be pivotable aboutan axis 62 to provide an adjustable launch angle. In an alternateembodiment, the drive pulley may be driven by the motor via a sprocketand chain. One example of this is shown in FIG. 14A.

In most operational specifications, the deployment and tear down time ofthe launching system are critical parameters. The time to set-up thesystem, bring it to ready mode, perform a launch, and then reset thesystem for subsequent launches is crucial. Because there is no timeassociated with a pressurization cycle or spinning up a flywheel whenusing this battery/motor/tape combination, the time to energize thesystem, which involves charging up a set of capacitors to achieve aready signal following system set-up, is minimal. The batteries can besized to achieve a number of launches before recharging is required. Ina specific embodiment, the batteries can be sized to allow four launchesto be achieved prior to recharging or before battery replacement isrequired. More or fewer launches may be provided per charge, dependingupon the size of the battery selected, the weight of the UAV to belaunched, and the speed of the motor required. Additional battery packscould be charged separately and swapped out to continue operation in thefield without waiting for on-board batteries to recharge. In oneembodiment, quick disconnects may be provided to speed the batterychange over process. A greater number of launches may be possible with alarger battery configuration, but this would impact system weight. Theweight to launch cycles can be optimized based on the customerrequirements.

In addition to the faster time to launch, the reset time for thedisclosed system is faster because retraction of the shuttle does notrequire the movement of hydraulic fluid back into the reservoir typicalof hydraulic/pneumatic launchers. To further enhance the reset time, thepayout reel 36 could be motorized to retract the shuttle 14 back intothe battery position 38.

In the systems described, in one example, the operator's station may bewired, but remote from the launcher. In another example, the operator'sstation may be made wireless. The systems may be designed so that onceset up with a UAV, they may be remote controlled.

Changes and modifications, additions and deletions may be made to thestructures and methods recited above and shown in the drawings withoutdeparting from the scope or spirit of the invention and the followingclaims.

What is claimed is:
 1. A launching system for an unmanned aerialvehicle, comprising: (a) a launcher rail; (b) a shuttle configured totravel along the launcher rail; (c) a drive mechanism for moving theshuttle along the launcher rail, the drive mechanism comprising (i) amotor-driven tape running along the launcher rail, the motor-driven tapehaving an interface that is detachably securable to an undercarriage ofthe shuttle, (ii) an electric drive motor that drives movement of thetape, and (iii) a power reel to which one end of the tape is secured andaround which the tape is wound during launch, wherein the shuttlereleases from the motor-driven tape during launch.
 2. The launchingsystem of claim 1, wherein the tape is wound onto the power reel duringlaunch to accelerate the shuttle.
 3. The launching system of claim 1,further comprising a payout reel having another end of the tape securedthereto.
 4. The launching system of claim 3, wherein the payout reel isused to rewind the tape following a launch sequence and re-position theshuttle into a launch ready position.
 5. The launching system of claim3, wherein the payout reel is motorized or manually rotated for rewindoperations.
 6. The launching system of claim 1, wherein the payout reelis positioned on a base plate below the launcher rail.
 7. The launchingsystem of claim 1, wherein the shuttle separates from the tape duringlaunch.
 8. The launching system of claim 1, wherein the shuttle to tapeinterface comprises a hook on the undercarriage of the shuttle and acorresponding protrusion on the tape.
 9. The launching system of claim1, wherein the shuttle to tape interface comprises a connection on theundercarriage of the shuttle and a corresponding connection feature onthe tape.
 10. The launching system of claim 1, wherein the shuttle totape interface comprises a connection on the shuttle that secures twoends of the tape to one another, such that the tape may bediscontinuous.
 11. The launching system of claim 1, wherein the electricdrive motor is stationary with respect to the launcher rail in use. 12.The launching system of claim 1, further comprising first and secondsheaves positioned at first and second ends of the launcher rail,wherein the tape is directed over the first and second sheaves.
 13. Thelaunching system of claim 1, wherein the tape is comprised of a materialthat offers a degree of cushioning during initial application of launchload.
 14. The launching system of claim 1, wherein the tape comprisesnylon or a nylon blend.
 15. The launching system of claim 1, wherein theelectric motor is a DC motor.
 16. The launching system of claim 1,wherein the electric motor is powered by one or more batteries orcapacitors.
 17. The launching system of claim 16, wherein the batterycomprises a lithium ion battery.
 18. The launching system of claim 1,wherein the electric drive motor and the power reel are positioned on abase plate below the launcher rail.
 19. The launching system of claim 1,wherein the tape comprises a first component of launch tape secured to aforward portion of the shuttle and a second component of arresting tapesecured to a rear portion of the shuttle.
 20. The launching system ofclaim 1, wherein the launcher rail is an inclined ramp.
 21. A launchingsystem for an unmanned aerial vehicle, comprising: (a) a launcher rail;(b) a motor-driven tape configured to travel a length of the launcherrail; (c) a shuttle secured to the tape at a shuttle to tape interface;(d) a power reel driven by an electric drive motor that drives movementof the tape; and (e) a payout reel, wherein the shuttle releases fromthe motor-driven tape during launch.
 22. The launching system of claim21, wherein the payout reel allows the tape to peel off in a controlledmanner during the launch sequence.
 23. The launching system of claim 21,wherein the payout reel is used to rewind the tape following a launchand move the shuttle into a launch ready position, decreasing the timeto reset the system for subsequent launch cycles.
 24. A launching systemfor an unmanned aerial vehicle, comprising: (a) a launcher rail; (b) ashuttle configured to travel along the launcher rail; (c) a drivemechanism for moving the shuttle along the launcher rail, the drivemechanism comprising (i) a motor-driven belt running along the launcherrail, the belt having an interface secured to the shuttle; (ii) anelectric drive motor that drives movement of the belt, and (iii) aconveyor that moves the belt in a loop, wherein the shuttle releasesfrom the motor-driven belt during launch.
 25. The launching system ofclaim 24, wherein the loop comprises a continuous loop.
 26. Thelaunching system of claim 24, wherein the loop comprises a discontinuousloop.
 27. The launching system of claim 1, wherein the motor-driven tapeis comprised of a material that has more elasticity or stretch than asteel cable.
 28. The launching system of claim 1, wherein themotor-driven tape is a flat tape.